In the last week, three young adults have died after taking apparent overdoses of a drug known on the street as “molly”— two of them over the Labor Day weekend at a New York electronic music festival.

Officials canceled the last day of the event after the deaths and reports that four other attendees were in critical condition after taking the drug. While molly has been around for decades under another name — it was popular among clubbers and psychedelic fans in the 1980s— it’s back again, enjoying a resurgence for its ability to boost feelings of warmth and intimacy. Here’s what experts say about separating fact from fiction.

1) Molly Is a new drug

Molly is the new street name for an old drug formerly known as Ecstasy— popularized in recent songs by Miley Cyrus and Kanye West. Ecstasy, or MDMA— 3,4-methylenedioxy-N-methylamphetamine is essentially speed with a psychedelic and empathetic twist. It can produce a sense of social closeness, bonding and euphoria, which explains its long-standing popularity among club- and party-goers. First synthesized by Merck in the early 1900s, it was not widely available in the U.S. until the 1980s.

In its latest incarnation, molly is supposedly a purer “molecular” (hence the nickname) version of MDMA, which in the past has been cut with everything from caffeine to various amphetamines. But there is no reason to expect that molly is less likely to be free of contaminants than any other illegal drug.

“Anybody who propagates the idea that this is purer than anything else— it’s ridiculous,” says Dr. Julie Holland, a psychiatrist in private practice and the editor of Ecstasy: The Complete Guide, “It’s a white powder. What could be more of a question mark? At least in a tablet someone put some time into putting it together. But [the name molly] sounds so innocent, like a girl in freckles and pigtails. It’s good marketing.”

In the U.S., use of MDMA rose in the early 2000s, with 15% of college students saying they had tried it in the year 2001. By 2012, its popularity had waned some; 7% of high school seniors and 9% of college students reported using it then.

2) Molly Is safer than other drugs because it’s purer

Since it is actually no more pure than other street drugs, molly’s reputation for safety is unjustified. “It’s anybody’s guess what they’re taking recreationally,” says Holland. Each hit can range from having no active drug at all to those that could potentially cause overdose. One common adulterant is PMA, which produces similar similar social bonding effects and belongs to the same class of amphetamine drugs. Many deaths originally attributed to MDMA were later found to be caused by this stand-in drug.

Even if the MDMA is actually MDMA, its risk comes from an ability to raise body temperature, which can cause life-threatening heat stroke, particularly when someone is dancing for hours in a hot, crowded club or concert.

3) Drinking water makes molly safer

While staying hydrated can reduce the risk of heat stroke associated with MDMA, the drug can also cause the body to retain water, so drinking too much can lead to a potentially fatal electrolyte imbalance.

“You only want to replace what you’re losing through sweat,” says Holland, who cautions against drinking excessive amounts of water. Sports drinks, which replace electrolytes, are actually safer to drink than tap water. And women may be at greater risk for over-hydrating than men, Holland says, because they tend to retain more water, especially before their menstrual periods.

That depends. Combining MDMA with alcohol, for example, dampens the high, while also increasing the risk of dehydration , which can lead users to seek out more MDMA and to drink more. Caffeine and other stimulants, however, do increase the effects of MDMA but can also boost the dangers, since they raise the risk of heat stroke by ratcheting up body temperature.

The federal government currently classifies MDMA as a Schedule One drug, which means it has no accepted medical use and a high potential for misuse— it’s in the same category as marijuana and heroin. That makes research on its effects difficult, but some scientists are investigating how it might help in treating conditions like post-traumatic stress disorder (PTSD). The drug acts on the brain chemical serotonin, which is involved in mood, and also seems to affect the “love hormone” oxytocin, which is involved in bonding. So the idea is to provide it to patients for a few therapy sessions only, as a way to build and restore a sense of trust and safety so that they can move past their traumatizing memories.

And so far, the results look promising. But that type of short-term, highly monitored use in treatment can’t compare to taking an illegal drug of uncertain purity in a chaotic environment among strangers. Its feel-good reputation may give users a false sense of security and obscure the drug’s risks. But as the recent deaths show, feeling good on molly may come with too high a price.